841 research outputs found

    An Economic Valuation of Pollination Services in Georgia

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    The production of many crops depends on biotic pollination. As pollinator populations decline, assessments of the potential consequential loss of economic value are critical. We estimate the economic value of pollination services ($608 million), crop vulnerability ratio (21 percent), and pollination’s contribution to agricultural production value (5 percent) for Georgia.Pollination, Colony Collapse Disorder, Georgia, Bioeconomic, Value, Vulnerability, Ecosystem Services, Crops, Honeybees, Pollinators, Pollination Dependency, Environmental Economics and Policy,

    Polar plasmas as observed by Dynamics Explorers 1 and 2

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    Plasma measurements from the Dynamics Explorer 1 and 2 satellites were used to characterize the polar cap environment. Analysis of numerous polar-cap passes indicate that, in general, three major regimes of plasma exist: (1) polar rain--electrons with magnetosheath-like energy spectra but much lower densities, most intense near the cusp and weakening toward the central polar cap; (2) polar wind--low energy upward flowing ions with both field-aligned and conical distributions; and (3) acceleration events--sporadic events consistent with the acceleration of electrons and positive ions by parallel electric fields. (1) to (3) were observed at high altitudes by Dynamics Explorer 1, while (1) and (3) were also observed at low altitudes by Dynamics Explorer 2. The plasma parameters associated with these plasma regimes are presented and discussed in terms of source and acceleration mechanisms

    Simulation of the Sedimentology of Sediment Detention Basins

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    Sediment detention basins are a widely used means of controlling downstream sediment pollution resulting from stripmining and construction activities. A mathematical model for describing the sedimentation characteristics of detention basins has been developed. This model requires as inputs the inflow hydrograph, inflow sediment graph, sediment particle size distribution, detention basin stage-area relationship and detention basin stage-discharge relationship. Based on this information the model routes the water and sediment through the basin. In this routing process the outflow sediment concentration graph, the pattern of sediment deposition in the basin and the sediment trapping efficiency are estimated. Comparison of predicted results with measured sediment basin performance indicates the model accurately represents the sedimentation process in detention basins. This report details the model, illustrates its use in design, explains how to process the model on a digital computer and presents a program listing of the model

    Modeling Soil Erosion with Emphasis on Steep Slopes and the Rilling Process

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    A soil erosion model, known as KYERMO, was developed for use in soil erosion research. The model was written in Microsoft FORTRAN, which is a subset of the ANSI FORTRAN 77 standard, allowing the model to be run on an IBM-PC as well as a mainframe computer. The model structure consisted of many interrelated subroutines which facilitated model development, testing, and future expansion. A sensitivity analysis of the detachment component was performed, examining the number of rills, the number of space and time steps, and the detachment parameters. This analysis indicated that the model performed as expected for the detachment limiting case. Field plots for the collection of justification data were designed and constructed on steep slopes (28 and 30.5 percent). Their surfaces were shaped to provide controlled rill patterns. Rainfall was applied through use of an irrigation nozzle rainfall simulator. The field simulations included initial full plot (22.1 m) runs on unrilled surfaces with two and six rill watersheds, full plot runs on established surfaces, and half plot runs on established surfaces. Eight field simulations were conducted. Measured or sampled quantities included runoff rate, delivered sediment concentration, delivered sediment size distribution, rainfall intensity, soil moisture content, plot surface shape, and rill cross-sections. Each of the field erosion events was simulated using KYERMO. Hydrologic parameters were fitted to provide the proper runoff characteristics to allow justification of the erosion component of the model. The detachment parameters were initially set using parameters and relationships from the literature. Prediction was comparable to that reported by other researchers. The detachment parameters were then fitted individually to gain insights about their effects. The resultant values were then considered in light of plot characteristics. These analyses indicated that a more complete knowledge of the rill bed particle size distribution could be used to increase accuracy and that soil structure changes due to tillage should be considered. The detachment rate was found to be the limiting factor rather than the sediment transport rate

    Modeling Erosion on Long Steep Slopes with Emphasis on the Rilling Process

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    A model of soil erosion, known as KYERMO, is presented which emphasizes those processes which are important on steep slopes. Particular emphasis is placed on modeling rill development and geometry since this is the least understood process in erosion mechanics. The model requires an input rill pattern. Rainfall inputs to the model require the use of breakpoint rainfall and kinetic energy. Surface storage is calculated based on random roughness data of Linden (1979). Infiltration is modeled by use of the two layer Green-Ampt-Mein-Larson model as proposed by Moore and Eigel (1981). Runoff is related to rainfall excess and surface storage by the exponential, relationship of Thelin and Keifer (1960). Erosion is modeled separately as rill and interrill erosion. Interrill erosion is modeled by evaluating raindrop splash and interrill transport capacity. Raindrop splash is predicted by using the Bubenzer and Jones (1971) equation which requires kinetic energy, rainfall intensity, and percent clay. In terr ill transport capacity is modeled by either the Yalin (1963) or Yang (1973) equation depending on user preference. The rate of delivery of soil to a rill is a minimum of either the transport rate or splash rate. Rill detachment capacity is calculated using the shear excess equation of Foster (1982). Transport capacity is calculated from either the Yalin (1963) or Yang ( 1973) depending on user preference. The distribution of detachment around the rill boundary is calculated as a function of the shear distribution. Shear is distributed by using a modification of the area method of Lundgren and Jonsson (1964). Rill wall sloughing is calculated by using the procedure of Wu et al. (1982) which uses a critical wall angle. Flow routing in rills is calculated by using the kinematic routing procedures of Brakensiek (1966). Data is presented showing that predictions made with model components are reasonable. A limited sensitivity analysis with the model shows that predictions follow the trends that one would expect

    Working Group 5: Measurements technology and active experiments

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    Technology issues identified by working groups 5 are listed. (1) New instruments are needed to upgrade the ability to measure plasma properties in space. (2) Facilities should be developed for conducting a broad range of plasma experiments in space. (3) The ability to predict plasma weather within magnetospheres should be improved and a capability to modify plasma weather developed. (4) Methods of control of plasma spacecraft and spacecraft plasma interference should be upgraded. (5) The space station laboratory facilities should be designed with attention to problems of flexibility to allow for future growth. These issues are discussed

    Simulating the Water Requirements and Economic Feasibility of Corn in the Midwest

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    An evaluation of the economics of supplemental irrigation when using a surface water supply must be site specific in order to account for variations in soil moisture holding capacity, watershed area supplying the runoff, climatic conditions, and proposed irrigation management procedures. With the use of farm specific simulation models to determine grain yields, availability of irrigation water, and economic expenditures involved in irrigation, an economic evaluation of supplemental irrigation can be performed, In the model presented in this report, the Duncan SIMAIZ model is used to predict grain yields using long-term daily weather information. SIMAIZ also determines irrigation water demand for the crop. The Haan Water Yield Model is used to predict flow into a reservoir using the same weather information. By knowing daily water flow into a reservoir and water demand for irrigation, a reservoir size is determined which will supply water at all times for the study period. Simulations are then run by incrementally reducing, by volume, the size of this reservoir, thus limiting the availability of irrigation water, and resulting in reduced irrigated yields. An economic evaluation is performed for each reservoir size. Costs and benefits included are: initial cost of constructing the reservoir, yearly reservoir maintenance cost, yearly irrigation costs of operation, and additional income resulting from the increase in grain yields. After the project life has been assumed, the model determines the capital available for investing in an irrigation system for a given year and reservoir size. By ranking these values, a probability distribution is obtained indicating the probability of making money in any given year. By using the Central Limit Theorem, these results are converted to the probability of making money over the life of the system. A sensitivity analysis examines the sensitivity of capital available for investment in an irrigation system to select input variation. The results indicate that great care should be exercised when assigning values to some inputs, while for others, a reasonable estimate is adequate. This model can be used as a tool for evaluating which irrigation practices, if any, are economically feasible. An example of its use is shown

    The 1974 NASA-ASEE summer faculty fellowship aeronautics and space research program

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    Research activities by participants in the fellowship program are documented, and include such topics as: (1) multispectral imagery for detecting southern pine beetle infestations; (2) trajectory optimization techniques for low thrust vehicles; (3) concentration characteristics of a fresnel solar strip reflection concentrator; (4) calaboration and reduction of video camera data; (5) fracture mechanics of Cer-Vit glass-ceramic; (6) space shuttle external propellant tank prelaunch heat transfer; (7) holographic interferometric fringes; and (8) atmospheric wind and stress profiles in a two-dimensional internal boundary layer

    Providing a Safe Harbor for Those Who Play by the Rules: The Case for a Strong Regulatory Compliance Defense

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    On September 25, 2003, a fire broke out at the National Health Care (NHC) nursing home facility in Nashville, Tennessee, causing sixteen deaths and a number of injuries from smoke inhalation. Thirty-two victims subsequently filed suit against the nursing home, alleging that NHC was negligent for failing to install sprinklers in its facility. This claim was made notwithstanding the fact that applicable federal, state, and local safety regulations did not require the installation of sprinklers in this particular type of building, and notwithstanding that the NHC facility had been inspected by state fire inspectors just months before the fire and was found to be in compliance with all requirements of the fire code. NHC eventually settled these lawsuits in order to avoid the uncertainty and expense of further litigation. The NHC case illustrates how good-faith compliance with applicable safety regulations provides businesses with almost no protection against potentially devastating tort liability. The problem is with the legal rule that governs compliance with government regulations. In effect, most courts treat a defendant\u27s compliance with governmental regulations as evidence of due care, but allow the jury to find that a defendant was negligent, notwithstanding his or her compliance with legislative or administrative regulations. We shall refer to this as the traditional approach to regulatory compliance. The traditional approach originated in Grand Trunk Railway Co. of Canada v. Ives, decided by the United States Supreme Court in the late nineteenth century. Later, § 288C of the Second Restatement of Torts endorsed this version of the rule, declaring that compliance with safety regulations was not conclusive evidence that a defendant exercised due care. The American Law Institute is currently in the process of drafting the Third Restatement of Torts, and the revised version of the regulatory compliance defense is substantially similar to that of the Second Restatement. In our view, there are many problems with the traditional approach. First, legislatures and administrative agencies have more expertise than lay juries when it comes to determining efficient levels of safety, but the traditional approach allows lay juries to second guess them. Second, under our constitutional system, legislative bodies and administrative agencies, not courts, are responsible for making resource allocation and other policy decisions. Therefore, courts should accept the trade-offs that are often embodied in safety regulations instead of allowing plaintiffs to use the litigation process to substitute their own policy choices for those of legislative bodies and administrative agencies. Third, the traditional approach wrongly assumes that government safety regulations merely set minimum standards, while, in reality, modem regulations typically reflect state-of-the-art standards. Thus, by adding jury-created safety standards on top of existing regulatory requirements, the traditional approach to regulatory compliance adds to the cost of doing business without achieving significant safety gains. Fourth, the traditional approach to regulatory compliance undermines the principle of uniform application of regulatory standards. Because jury verdicts are seldom consistent, business entities are often subjected to nonuniform safety standards. Finally, the traditional approach deters useful economic activity by imposing potentially crushing tort liability upon those who have complied in good faith with regulatory standards. Part II of this Article examines the traditional approach to the regulatory compliance defense, beginning with the Supreme Court\u27s opinion in Grand Trunk Railway Co. of Canada v. Ives, and proceeding to the Restatement (Second) § 288C and the Restatement (Third) of Torts: Liability for Physical Harm § 16. In Part III, we discuss a number of cases that explicitly recognize a strong regulatory compliance defense, as well as cases that achieve a similar objective by expressly or impliedly applying the Second Restatement\u27s § 16, comment (a) exception. Part IV reviews some of the arguments that support a stronger regulatory compliance defense. These include: (1) the institutional competence argument, (2) the separation of powers argument, (3) the regulatory efficiency argument, (4) the nonuniform standards argument, and (5) the overdeterrence argument. In Part V, we focus on nursing home regulation to -see what impact a stronger regulatory compliance defense would have on this socially useful industry. Finally, in Part VI, we set forth a proposed alternative to the current version of Restatement (Third) of Torts: Liability for Physical Harm § 16
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